Technical Bulletins - Germany r - Xs4all

Translation of the German Technical Product
Bulletin
Deoxidizer 6 (sulphuric
acidic)
Deoxidizing product for aluminum
- liquid, chromic acid containing product -
Fields of application: A solution of sulphuric acid or nitric acid containing the Deoxidizer 6
removes oxides and alkali residues of former alkaline degreasing or
etching processes on aluminum and its alloys.
Deoxidizer 6 can be used in immersion and spray processes.
Process components: Deoxidizer 6
Deoxidizer 16
Sulphuric acid (ca. 96 %) or nitric acid (ca. 60 %)
Bath make-up: For the preparation of 1000 l of the Deoxidizer 6 solution in sulphuric
acid add to 500 l of water under stirring :
Sulphuric acid (ca. 96 %) 92 kg or 50 l
Deoxidizer 6 57 kg or 50 l
After complete dissolution fill up with water to 1000 l.
Operating conditions: Free acid-points 18 - 20
Cr ( VI ) -points 13 - 15
Temperature 20 - 40 °C
Time 1 - 10 min

Process sequence: 1. Clean/Pickle
2. Rinse
3. Deoxidize with Deoxidizer 6
4. Rinse
5. Conversion coating
6. Rinse
7. Rinse with DI-water
8. Dry
Maintenance of the bath: The Deoxidizer 6 bath is controlled by a titration of the free acid-points
and the Cr(VI)-points.
Free acid-points: Titration:
1. Pipette 10 ml sample of the Deoxidizer 6 bath into a flask and dilute
with 50 ml of distilled water.
2. Add 4 - 5 drops of bromkresolgreen.
3. Titrate against 1 N caustic solution until the colour changes from
yellow to green.
4. Record the number of ml of 1 N caustic solution used as free
acid-points.
Replenishment: Add 5.5 kg or 3 l of sulphuric acid (ca. 96 %) per 1000 l of the bath for
each free acid-point lacking.
Cr(VI)-points: Titration:
The bath should be kept within 18 - 20 free acid-points.
1. Pipette 5 ml sample of the Deoxidizer 6 bath into a flask and dilute
with 50 ml distilled water.
2. Add 20 ml of 25 % H 2 SO 4 and 2 - 3 g KJ.
3. Titrate against 0.1 N sodium thiosulphate solution until the colour
changes from brown to yellow.
4. Add 1 - 2 ml of the starch solution to the sample and continue the
titration until the blue-black colour disappears.
5. Record the number of ml of 0.1 N sodium thiosulphate solution used
as Cr(VI)-points.
Replenishment: Add 3.8 kg or 3.3 l Deoxidizer 16 per 1000 l of the bath for each
Cr(VI)-point lacking.
The bath should be kept within 13 - 15 Cr(VI)-points.
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Remarks: The tank material containing the Deoxidizer 6 bath should be made out
of rigid PVC (free of plasticizer) or austenic steel (type No. 1.4571).
Spraying systems, pumps and heat exchangers have to be made out of
stainless steel (type No. 1.4571).
Bathes of Deoxidizer 6 as well as the subsequent rinsing bath are not
to be discharged into the public sewage system without prior
detoxification and neutralization.
Caution: Deoxidizer 6 contains chromium trioxide and hydrofluoric acid. Wear
- Eye goggles
- Rubber gloves
- Acid resistant wear
Avoid contact with skin.
Provide air circulation.
Equipment and chemicals
for the analysis: Pipet, 5 ml
Pipet, 10 ml
Erlenmeyer flask, 300 ml
Graduated cylinder, 50 ml
Buret, 25 ml
DI-water
Alcoholic bromcresol green solution, 0.1 %
Caustic solution, 1 N
Sulphuric acid, 25 %, pur
Potassium iodide
Starch solution (stabilized), 1 %
Sodium thiosulphate solution, 0.1 N
The expiry date of the product is given on the packaging labels.
This information is based on our current level of knowledge. It is given in good faith but it is not intended to guarantee any
particular properties. The users must satisfy themselves that there are no circumstances requiring additional information or
precautions or the verification of details given herein.
Henkel Oberflächentechnik GmbH
40191 Düsseldorf
Telefon +49 211 797 3000
Telefax +49 211 798 3636
Revision date: 05-03-2001
Henkel Teroson GmbH
Postfach 10 56 20
69046 Heidelberg
Telefon +49 6221 704 0
Telefax +49 6221 704 698
Henkel Oberflächentechnik GmbH
Geschäftseinheit Wasserbehandlung
D-40191 Düsseldorf
Telefon +49 211 797 9190
Telefax +49 211 798 2262
11-09-2002 Deoxidizer 6 (sulphuric acidic) - 3 -